||P.276 bottom paragraph: "In a young adult mouse the thymus contains about 10^8 to 2x10^8 thymocytes." Thymocytes are T cell precursors which develop in the thymus. See same value in Tough et al., (1995) PMID 7613491, p.243 left column 2nd paragraph: "T cells are produced in the thymus and exported in small numbers to the peripheral lymphoid tissues [ref 1]. The size of the mature peripheral T cell pool increases progressively with age and reaches adult levels (˜2X10^8 cells in mice) at the time of puberty. Thereafter, peripheral T cell numbers remain relatively constant."